Tony Duell has written
utilities
for formatting TRS-80 disks in an
Intel Linux PC with a standard PC disk controller
and copying .dsk images to them. Right now the utilities work
only for standard double-density LDOS5/TRSDOS6/LS-DOS6 formats, 18
sectors/track, 256 bytes/sector, 40 or 80 tracks/side, and 1 or 2
sides. They are handy if you can't run
xtrs (perhaps you don't have
X on your Linux box) or you haven't gotten around to setting it up.

Full documentation for the Western Digital 1771 and 179x floppy
disk controller chips used in TRS-80 Models I/III/4 is now available
from David Keil's documentation preservation pages. He has scans of
the original data sheets and application notes for the 1771 and 179x.

Earlier, I found partial documentation for the Western Digital 1791
and 1793 floppy disk controllers at an ORIC Web site. That site
seems to have gone away, so you can get a copy of the document from here.

Another useful item I found on the Web is zmac, a
free Z-80 cross-assembler for Unix. Mark Rison has taken over
maintenance of zmac and released a new version, 1.3. You can download
it here or from Mark's CPC/IP page. You can
make TRS-80 cmd files with zmac by running "zmac -h" to create an
Intel hex file, then using the program hex2cmd included with my version of xtrs.

Later I found a file on Compuserve that gives technical specs for
Radio Shack's Model 4 hi-res card,
including some ports that Radio Shack didn't document. This file was
written in 1985 by Compuserve member Paul Bradshaw.

I haven't found any documentation for the Micro Labs Model III hi-res
card, but I did find some software that works with it, so I was able to
reverse-engineer what the hardware does. Here is what I learned.

Radio Shack's Model III hi-res card is the same as the Model 4 card
except that the undocumented features of the Model 4 card are not
present. That is, graphics are always 640x240, text and graphics
cannot be overlayed, and there are no scrolling registers. There is a
scan of the manual for this card on Wade Fincher's
TRS-80 page.

In 1998 I helped reconstruct a lost program by reassembling it
from source code that had been written with the ASM6 assembler for the
Model 4. ASM6 saves source code in a proprietary compressed format
similar to tokenized Basic programs. I didn't have a copy of ASM6, so
I reverse-engineered the format.

In 2012, Vernon Hester contacted me and told me that the tokenized
format I reverse-engineered in 1998 looks exactly the same as the one
from his ZEUS assembler. At this point we don't know why. At any
rate, Vernon sent me a copy of the complete list of tokens, as I had
been missing a few.

If you need to decode a ZEUS or ASM6 save
file, feel free to use my
program. See the comments at the top for instructions.

I've scanned in the user manual
(Word 97,
Acrobat)
and the schematic (JPEG) for the
Lobo LX-80 Expansion Interface. The LX-80 was an alternative to the
Radio Shack Expansion Interface for the Model I. It was not at all
hardware compatible with the Radio Shack interface, but offered
additional capabilities such as 8-inch floppy drive support and two
serial ports. My copy of the schematic was not very good; please let
me know if you have a better one and can fill in missing details.

Here is a collection of Lobo MAX-80 materials sent to me by Tom
Burnett. Tom has been gearing up to work on a MAX-80 emulator,
possibly based on xtrs, possibly on MESS. The manual scans were done
by a friend of Tom's, the late John Ray.

In 2001 I helped someone recover the manuscript of an old book
from some Model II Scripsit disks. This was pretty tricky, since I
don't have a Model II, there are no Model II emulators, and Model II
Scripsit uses a strange, proprietary file format. Here are some
details in case anyone else wants to do this.

The next trick was to get the DOCUMENT/CTL files off the Model II
TRSDOS 2.0a disk images. It turns out that the version of CONV/CMD
that came with Model II LS-DOS 6.3.1 can read Model II TRSDOS 2.0
disks and copy the files to LS-DOS disks. I got a copy off the Model
II LS-DOS disk image from my Misosys software
page. Although this image obviously won't boot on a Model 4
emulator, Model 4 LS-DOS can read it as a data disk, and many of the
programs will run, including CONV/CMD. Unfortunately I found that
CONV/CMD has a bug; it assumes the TRSDOS directory is always on track
44, but the diskettes I was looking at had it on track 1. This patch
makes it look on track 1 instead: PATCH CONV/CMD.UTILITY (X'30A6'=01)
After that, I exported the DOCUMENT/CTL files to Unix using
xtrs's EXPORT/CMD utility.

Now I was stuck for a while. DOCUMENT/CTL files are in a strange
format I had never seen before. The file takes up the whole
floppy disk and has its own built-in directory that can contain
several documents. Blocks of the documents and arrays of pointers
are scattered all over. But I spent a Saturday poring over
one of the files with a hex editor, and ended up writing a C program
called scripsitx
that finds all the documents and extracts the text from each to a file.
I also wrote a little program
scr2txt
that translates some odd special characters that Scripsit uses in
its files, such as 0x8d for end-of-paragraph, to a more reasonable
ASCII representation.